Contiguous disk patterns were discussed in a paper entitled "Crystal Symmetry Effects in Ion-implanted Propagation Patterns for Magnetic Bubbles--Roof-top Designs" by Wolfe and Nelson in IEEE Trans. Magnetics, MAG 15, 1323 (1979). FIG. 1A was disclosed in that paper. FIG. 1A describes a roof-top major loop design 10 having a triangular type track 12 of the elements 14, 18, 16 and 20. These elements are arranged so that their cusps are oriented such that one of the three crystal axes, in this case the (1,1,2) axis, is either +30.degree. or -30.degree. from the line bisecting the cusp angle.
Another contiguous bubble device propagation pattern by C. C. Shir, disclosed in IBM Technical Disclosure Bulletin Vol. 23 No. 5 page 2112, October 1980, is shown in FIG. 1B. The propagation tracks are parallel to one of the following three crystal directions: (1,1,2), (1,2,1) and (2,1,1). Every cusp is oriented such that one of the three crystal axes mentioned above is substantially bisecting the cusp angle.